Connect public, paid and private patent data with Google Patents Public Datasets

Use of mixed hydroxyethers as auxiliaries for the dehydration of solids

Download PDF

Info

Publication number
US5215669A
US5215669A US07777389 US77738991A US5215669A US 5215669 A US5215669 A US 5215669A US 07777389 US07777389 US 07777389 US 77738991 A US77738991 A US 77738991A US 5215669 A US5215669 A US 5215669A
Authority
US
Grant status
Grant
Patent type
Prior art keywords
sub
water
solids
used
surfactant
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related
Application number
US07777389
Inventor
Rita Koester
Maria Liphard
Gilbert Schenker
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HENKEL (HENKEL KGAA) A CORP OF FEDERAL REPUBLIC OF GERMANY KGaA
Henkel AG and Co KGaA
Original Assignee
Henkel AG and Co KGaA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Grant date

Links

Images

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26DRYING
    • F26BDRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00Drying solid materials or objects by processes not involving the application of heat
    • F26B5/005Drying solid materials or objects by processes not involving the application of heat by dipping them into or mixing them with a chemical liquid, e.g. organic; chemical, e.g. organic, dewatering aids

Abstract

The use of mixed hydroxyethers of the general formula I
R.sup.1 O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 --CH(OH)R.sup.2 (I)
in which
R1 denotes an alkyl group having 1 to 10 carbon atoms
R2 denotes an alkyl group having 8 to 20 carbon atoms and x denotes a number in the range from 1 to 20 as auxiliaries for the dehydration of water-containing finely divided solids, gives solids having a low water content without foaming in the water separated therefrom.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to the use of mixed hydroxyethers of the general formula I

R.sup.1 O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 -CH(OH)R.sup.2 (I)

in which

R1 denotes an alkyl group having 1 to 10 carbon atoms,

R2 denotes an alkyl group having 8 to 20 carbon atoms and x denotes a number in the range from 1 to 20 as auxiliaries for the dehydration of water-containing finely divided solids.

2. Discussion of Related Art

In many branches of industry, e.g. in mining or in sewage treatment plants, large amounts of finely divided solids having high water contents, which have to be dehydrated before further processing of the solids or their disposal, are formed. Thus, for example, the dehydration of water-containing coal or coke is a central process in the processing of fuels based on coal. The maximum allowable values for the water content of these materials demanded by the market can often be adhered to only with difficulty, since, for example, the coal supplied is produced in very fine particles due to the extensive mechanization of the underground coal mining. Currently, about 38% of the run-of-mine coal is fines having a particle diameter in the range from 0.5 to 10 mm; a further 14% is duff having a particle diameter below that.

It is known to use surfactants as dehydration auxiliaries for the dehydration of water-containing finely divided solids, in particular coals, which make it possible to reduce the residual moisture of fines and duff. This is explained by the property of the surfactant to reduce the surface tension and the capillary pressure of water in the material to be extracted. At the same time, this reduces the adhesive energy which must be supplied to remove the surface water. This leads to improved dehydration, when surfactants are used, while the amount of energy remains unchanged.

Dialkyl sulfosuccinates (U.S. Pat. No. 2,266,954) and nonionic surfactants of the type of alkylphenol polyglycol ethers [Erzmetall 30, 292 (1977)] have been described as surfactant-based dehydrating auxiliaries of the above-mentioned types. However, these surfactants have the disadvantage of showing excessive foaming, which leads to considerable problems in the processing plants, in particular in the recirculation of the water which is usually employed.

DESCRIPTION OF THE INVENTION

Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term "about".

The invention is based on the finding that nonionic surfactants of the general formula I increase the dehydration rate without foaming and reduce the residual moisture of the dehydrated solids when employed in water/solid systems.

The group R1 of the mixed hydroxyethers to be used according to the invention of the general formula I is a straight-chain or branched or cyclic alkyl group having 1 to 10 carbon atoms, for example a methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl or decyl group. Alkyl groups of the above list having 1 to 4 carbon atoms are preferred. The group R2 in the general formula I is an alkyl group having 8 to 20 carbon atoms, for example an octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl or eicosyl group, in particular an alkyl group from the above list having 12 to 16 carbon atoms, straight-chain radicals R2 being particularly preferred. x in the general formula I is a number in the range from 1 to 20, the range from 2 to 15 being preferred.

In accordance with their use according to the invention, the mixed hydroxyethers of the general formula I have to be water-soluble. It may occur that the water solubility is not quite sufficient, if the mixed hydroxyethers of the general formula I have low values of x and long-chain radicals R1 and/or R2 where the chain lengths are within the abovementioned limits; however, the required water solubility can be obtained by increasing the value for x within the abovementioned range.

The mixed hydroxyethers of the general formula I are described in DE-A 3,723,323; they can be obtained by reacting ethoxylated alcohols of the general formula II

R.sup.1 O--(CH.sub.2 CH.sub.2 O).sub.x --OH                (II)

with epoxides of alpha-olefins of the formula III ##STR1## in the presence of catalysts, in which R1, R2 and x are as defined above.

In accordance with their preparation and the starting materials used, which are in most cases employed in the form of technical grade mixtures, the mixed hydroxyethers to be used according to the invention of the general formula I can also be present as technical grade mixtures.

In accordance with an advantageous embodiment of the invention, the mixed hydroxyethers of the general formula I are used in an amount of 0.5 to 10, in particular 3 to 8, kg per m3 of the water to be removed from the finely divided solids.

As mentioned at the beginning, the mixed hydroxyethers of the general formula I are suitable in particular for the dehydration of water-containing finely divided coal or coke; however, they can also be used in the dehydration of other water/solid systems, for example for beneficiated ores or gangue materials in ore mining, sewage sludges and the like. In this respect, a further advantage of the surfactants to be used according to the invention of the general formula I is that they are compatible with surfactants of different composition, which may be present, for example with dialkyl sulfosuccinates such as di-noctyl sulfosuccinates or polyacrylamides, which were added to the solids to be dehydrated in previous processing steps.

The invention is illustrated in more detail below by way of preferred embodiments.

In the examples, washed fines having the following analytical data were used:

6.8 % by weight of water

3.7 % by weight of ash (wf; calculated with respect to water-free coal)

27.2 % of volatile components (waf; calculated with respect to water- and ash-free coal)

Screen analysis of the fines gave the following values:

______________________________________-0.5       mm          1.5%0.5-2.0    mm          23.1%2.0-6.3    mm          51.5%+6.3       mm          23.9%.______________________________________

The efficiency of the mixed hydroxyethers of the general formula I in the dehydration was determined by treating the fines with aqueous solutions of the mixed hydroxyethers of defined concentration and dehydrating them under defined conditions; the residual moisture obtained with and without the addition of surfactant was determined according to DIN 51718 by drying at 106° C. and weighing.

The present examples are laboratory tests in which the amounts of surfactants used in kg are based on 1000 kg each of the solids to be dehydrated (calculated as waterfree solids). In practice, the necessary amounts of surfactants will be less than the ones used in the examples; moreover, the necessary amounts of surfactants used depend on the amount of the water to be removed from the solids, when the solids are dehydrated in practice.

The structure of the mixed hydroxyethers tested of the general formula I and their abbreviations used below can be seen from Table 1.

The term "surfactant" used here and hereinafter refers to the mixed hydroxyethers of the general formula I.

              TABLE 1______________________________________Mixed hydroxyethers of the formula IR.sup.1 O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 --CH(OH)R.sup.2Surfactant   R.sup.1     R.sup.2  x______________________________________A            CH.sub.3    n-C.sub.12 H.sub.25                             2B            CH.sub.3    n-C.sub.12 H.sub.25                             4C            n-C.sub.4 H.sub.9                    n-C.sub.12 H.sub.25                             2D            n-C.sub.4 H.sub.9                    n-C.sub.16 H.sub.33                             2______________________________________
EXAMPLE 1 Dehydration in a pressure filter

50 g of coal were added to 400 ml of distilled water or surfactant solutions in distilled water and were filtered after being exposed for 60 seconds. This was done by using a pressure filter which consisted of a sealed neutral filter which was filled with the material to be dehydrated. The dehydration was carried out by subjecting the filter to a pressure of 3 bar. The dehydration time was 30 seconds. The filter material used was a filter fabric having a mesh size of 0.2 mm.

The surfactants tested, the surfactant concentration of the solution with which the coal was treated, the amount of surfactant calculated per 1000 kg of coal and the residual moisture determined are summarized in Table 2.

              TABLE 2______________________________________Pressure filter test    Surfactant  Amount of sur-    concentra-  factant (kg) Residual    tion        per 1000 kg  moistureSurfactant    (g/l)       of coal      (% by wt.)______________________________________A        1.0         8            8.9B        1.0         8            8.5C        1.0         8            7.2D        1.0         8            9.9without the    --          --           11.6addition ofsurfactant______________________________________

As can be seen from Table 2, the residual moisture of the dehydrated coal is substantially reduced, when the surfactants to be used according to the invention are used compared with that without the addition of surfactant.

EXAMPLE 2 Dehydration in a centrifuge

In this example, a bucket-type centrifuge was used with which at revolutions of 300 to 3,400 per minute centrifugal characteristic values of 15 to 2000 can be obtained. Perforated plates having sieve openings of 0.4 ×4.0 mm were used as sieve plate for the centrifuge. The surfactants used as filtering aids (mixed hydroxyethers of the general formula I) were dissolved in distilled water in concentrations of 0.1 g/1 and 1.0 g/1. To carry out the tests, 400 ml each of the surfactant-containing solutions were poured into a glass vessel. 25 g of coal were dipped into each of these solutions. The wetting time was in each case 60 seconds. This was followed by predehydration of the samples at a constant dripping time of 180 seconds. The values obtained in the predehydration of the samples, the surfactant concentration and the amount of surfactant calculated per 1000 kg of coal are summarized in Table 3.

To dehydrate the predehydrated samples in the bucket-type centrifuge, centrifugal characteristic values of 43.2, 111 and 389 (corresponding to revolutions of 500, 800 and 1500 per minute) were established. The dehydration time was 30 seconds. The results obtained are summarized in Table 4.

In a second test series, a surfactant concentration of 1.0 g/1 at a centrifugal characteristic value of 111 (corresponding to revolutions of 800 per minute) was tested at dehydration times of 5, 10 and 30 seconds. The results obtained are summarized in Table 5.

As can be seen from Tables 3 to 5, all surfactants tested have a very good effect on the dehydration. Even in the predehydration (Table 3), the efficiency of the surfactants compared with a sample without the addition of surfactant became obvious. While the untreated sample had a residual moisture of 43.6% after a dripping time of 180 seconds, this value could be reduced down to 26.5% by means of the surfactants used according to the invention. This corresponds to a relative reduction in residual moisture by 39%.

As can be seen from Tables 4 and 5, the residual moisture could be reduced not only by increasing the centrifugal characteristic value but also by adding the surfactants to be used according to the invention.

A surfactant solution of 0.1 g/1 made it possible to reduce the residual moisture to 4.0% by weight at a centrifugal characteristic value of 111. A surfactant solution of 1.0 g/1 decreased the residual moisture down to 3.0%. These values can also be reached with short dehydration times.

              TABLE 3______________________________________Centrifuge testResults of the predehydration                Amount of sur-    Surfactant  factant (kg) Residual    concentra-  per 1000 kg  moistureSurfactant    tion (g/l)  of coal      (% by wt.)______________________________________A        1.0         16           26.5B        1.0         16           30.3C        1.0         16           30.1D        1.0         16           34.8without  --          --           43.6surfactantA        0.1           1.6        37.5B        0.1           1.6        31.9______________________________________

              TABLE 4______________________________________Centrifugal dehydration______________________________________Revolutions      500    800     1500  500   800  1500per minuteCentrifugal      43.2   111     389   43.2  111   389characteristicvalueSurfactant 0.1    0.1     0.1   1.0   1.0  1.0concentra-tion (g/1)Surfactant Residual moistureA          5.7    5.3     3.5   3.6   3.1  2.6B          4.5    4.0     3.7   3.7   3.0  2.5C          5.8    4.7     3.1   6.0   4.8  3.3D          6.9    5.9     4.1   7.0   5.2  3.7without addition      7.8    6.1     3.9   7.8   6.1  3.9of surfactant______________________________________

              TABLE 5______________________________________Results at a centrifugal characteristic value of 111______________________________________Dehydration  5          10       30time(s)Surfactant   Residual moisture (% by wt.)A            3.6        3.2      3.1B            3.8        3.5      3.0C            5.5        5.1      4.8D            5.7        5.5      5.2without surfactant        6.8        6.7      6.1______________________________________

Claims (10)

What is claimed is:
1. The process of dehydrating water-containing finely divided solids, comprising contacting said solids with a water-soluble mixed hydroxyether of formula I
R.sup.1 O--(CH.sub.2 CH.sub.2 O).sub.x --CH.sub.2 --CH(OH)R.sup.2 (I)
wherein R1 represents an alkyl group having 1 to 10 carbon atoms, R1 represents an alkyl group having 8 to 20, said mixed hydroxyether being present in an amount of from about 0.5 to about 10 kg per m3 of the water to be removed from said solids, and then filtering or centrifuging said solids.
2. The process as in claim 1 wherein R1 represents an alkyl group having 1 to 4 carbon atoms.
3. The process as in claim 1 wherein R2 represents an alkyl group having 12 to 16 carbon atoms.
4. The process as in claim 1 wherein x represents a number from about 2 to about 15.
5. The process as in claim 1 wherein said mixed hydroxyether is present in an amount of from about 3 to about 8 kg per m3 of the water to be removed from said solids.
6. The process as in claim 1 wherein said solids are selected from the group consisting of finely divided coal and coke.
7. The process as in claim 1 wherein said solids are selected from the group consisting of beneficiated ores and gangue materials.
8. The process as in claim 1 wherein said solids are selected from the group consisting of sewage sludges.
9. The process as in claim 1 wherein said mixing hydroxyether is present in an aqueous system.
10. The process as in claim 1 wherein said filtering step is conducted under pressure.
US07777389 1989-06-05 1990-05-28 Use of mixed hydroxyethers as auxiliaries for the dehydration of solids Expired - Fee Related US5215669A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE3918274 1989-06-05
DE19893918274 DE3918274A1 (en) 1989-06-05 1989-06-05 Use of hydroxy mixed as a tool for the feststoffentwaesserung

Publications (1)

Publication Number Publication Date
US5215669A true US5215669A (en) 1993-06-01

Family

ID=6382085

Family Applications (1)

Application Number Title Priority Date Filing Date
US07777389 Expired - Fee Related US5215669A (en) 1989-06-05 1990-05-28 Use of mixed hydroxyethers as auxiliaries for the dehydration of solids

Country Status (5)

Country Link
US (1) US5215669A (en)
CA (1) CA2058440C (en)
DE (1) DE3918274A1 (en)
EP (1) EP0475969B1 (en)
WO (1) WO1990015295A1 (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5372727A (en) * 1990-06-15 1994-12-13 Henkel Kommanditgesellschaft Auf Aktien Auxiliaries for the filtration and/or dewatering of mineral and coal suspensions
US5492631A (en) * 1992-06-01 1996-02-20 Henkel Kommnaditgesellschaft Auf Aktien Process for dewatering fine-particle solids suspensions using dialkyl carbonates
US5545332A (en) * 1992-06-01 1996-08-13 Henkel Kommanditgesellschaft Auf Aktien Process for dewatering fine-particle solids suspensions
US5670056A (en) * 1995-04-17 1997-09-23 Virginia Tech Intellectual Properties, Inc. Chemical-mechanical dewatering process
WO2002026340A2 (en) 2000-09-28 2002-04-04 Yoon Roe Hoan Methods of using natural products as dewatering aids for fine particles
US6375853B1 (en) * 2000-03-17 2002-04-23 Roe-Hoan Yoon Methods of using modified natural products as dewatering aids for fine particles
US6526675B1 (en) 1999-06-07 2003-03-04 Roe-Hoan Yoon Methods of using natural products as dewatering aids for fine particles
US6799682B1 (en) 2000-05-16 2004-10-05 Roe-Hoan Yoon Method of increasing flotation rate
US6855260B1 (en) 1999-06-07 2005-02-15 Roe-Hoan Yoon Methods of enhancing fine particle dewatering
US20060087562A1 (en) * 2004-10-26 2006-04-27 Konica Minolta Photo Imaging, Inc. Image capturing apparatus
US20060251566A1 (en) * 2005-02-04 2006-11-09 Yoon Roe H Separation of diamond from gangue minerals

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3194758A (en) * 1961-05-24 1965-07-13 Petrolite Corp Method of agglomerating finely divided solids in an aqueous medium
US4385903A (en) * 1980-11-18 1983-05-31 Kao Soap Co., Ltd. Agent for promoting filtration dehydration of metal hydroxide slurry
WO1985003065A1 (en) * 1984-01-09 1985-07-18 The Dow Chemical Company Mineral dewatering method
US4559143A (en) * 1979-07-10 1985-12-17 Nichikeri Chemical Industry Co. Ltd. Sludge treating method
US4925587A (en) * 1987-07-15 1990-05-15 Henkel Kommanditgesellschaft Auf Aktien Hydroxy ethers, a process for their production, and methods for their use
US4990264A (en) * 1989-10-13 1991-02-05 Sherex Chemical Company, Inc. Ore dewatering process and compositions therefor

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2266954A (en) * 1939-08-26 1941-12-23 American Cyanamid Co Wetting agent in settling of oe pulps
US2975123A (en) * 1957-11-04 1961-03-14 Int Nickel Co Dewatering metal ore concentrates
US3327402A (en) * 1964-12-28 1967-06-27 Shell Oil Co Solvent drying of coal fines
FR1462314A (en) * 1965-02-12 1966-04-15 Glaverbel A method of uniform lowering of the water retention capacity of a powdered material, and the resulting product
US4014104A (en) * 1975-06-23 1977-03-29 Continental Oil Company Drying of lignite using nonaqueous solvents
US4866856A (en) * 1987-10-13 1989-09-19 The Standard Oil Company Solids dewatering process and apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3194758A (en) * 1961-05-24 1965-07-13 Petrolite Corp Method of agglomerating finely divided solids in an aqueous medium
US4559143A (en) * 1979-07-10 1985-12-17 Nichikeri Chemical Industry Co. Ltd. Sludge treating method
US4385903A (en) * 1980-11-18 1983-05-31 Kao Soap Co., Ltd. Agent for promoting filtration dehydration of metal hydroxide slurry
WO1985003065A1 (en) * 1984-01-09 1985-07-18 The Dow Chemical Company Mineral dewatering method
US4925587A (en) * 1987-07-15 1990-05-15 Henkel Kommanditgesellschaft Auf Aktien Hydroxy ethers, a process for their production, and methods for their use
US4990264A (en) * 1989-10-13 1991-02-05 Sherex Chemical Company, Inc. Ore dewatering process and compositions therefor

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5372727A (en) * 1990-06-15 1994-12-13 Henkel Kommanditgesellschaft Auf Aktien Auxiliaries for the filtration and/or dewatering of mineral and coal suspensions
US5545332A (en) * 1992-06-01 1996-08-13 Henkel Kommanditgesellschaft Auf Aktien Process for dewatering fine-particle solids suspensions
US5492631A (en) * 1992-06-01 1996-02-20 Henkel Kommnaditgesellschaft Auf Aktien Process for dewatering fine-particle solids suspensions using dialkyl carbonates
US5670056A (en) * 1995-04-17 1997-09-23 Virginia Tech Intellectual Properties, Inc. Chemical-mechanical dewatering process
US20080053914A1 (en) * 1999-06-07 2008-03-06 Yoon Roe H Methods of Enhancing Fine Particle Dewatering
US7820058B2 (en) 1999-06-07 2010-10-26 Mineral And Coal Technologies, Inc. Methods of enhancing fine particle dewatering
US6526675B1 (en) 1999-06-07 2003-03-04 Roe-Hoan Yoon Methods of using natural products as dewatering aids for fine particles
US6855260B1 (en) 1999-06-07 2005-02-15 Roe-Hoan Yoon Methods of enhancing fine particle dewatering
US20050139551A1 (en) * 1999-06-07 2005-06-30 Roe-Hoan Yoon Methods of enhancing fine particle dewatering
US6375853B1 (en) * 2000-03-17 2002-04-23 Roe-Hoan Yoon Methods of using modified natural products as dewatering aids for fine particles
US6799682B1 (en) 2000-05-16 2004-10-05 Roe-Hoan Yoon Method of increasing flotation rate
WO2002026340A2 (en) 2000-09-28 2002-04-04 Yoon Roe Hoan Methods of using natural products as dewatering aids for fine particles
US20060087562A1 (en) * 2004-10-26 2006-04-27 Konica Minolta Photo Imaging, Inc. Image capturing apparatus
US20060251566A1 (en) * 2005-02-04 2006-11-09 Yoon Roe H Separation of diamond from gangue minerals
US8007754B2 (en) 2005-02-04 2011-08-30 Mineral And Coal Technologies, Inc. Separation of diamond from gangue minerals

Also Published As

Publication number Publication date Type
EP0475969A1 (en) 1992-03-25 application
EP0475969B1 (en) 1994-04-27 grant
DE3918274A1 (en) 1990-12-06 application
WO1990015295A1 (en) 1990-12-13 application
CA2058440C (en) 2001-03-27 grant
CA2058440A1 (en) 1990-12-13 application

Similar Documents

Publication Publication Date Title
Chang et al. Lime pretreatment of crop residues bagasse and wheat straw
Largeau et al. Formation of Botryococcus-derived kerogens—Comparative study of immature torbanites and of the extent alga Botryococcus braunii
US5434279A (en) Process for preparing fatty acid esters of short-chain monohydric alcohols
Williams et al. Levels of inorganic and total phosphorus in lake sediments as related to other sediment parameters
US4734205A (en) Hydrophobically associating polymers for oily water clean-up
US6526675B1 (en) Methods of using natural products as dewatering aids for fine particles
US5453133A (en) Soil remediation
Norin et al. Evidence for the presence of arsenobetaine and another organoarsenical in shrimps
US4251229A (en) Stabilized fuel slurry
Harada et al. Maturing process of city refuse compost during piling
US3898134A (en) Process and apparatus for recovering clean water and solids from dilute, aqueous, solids containing solutions or dispersions
US3974116A (en) Emulsion suspensions and process for adding same to system
US4309282A (en) Process of phosphate ore beneficiation in the presence of residual organic polymeric flocculants
Miller et al. Determination of the mineral-matter contents of coals by low-temperature ashing
US4474616A (en) Blending tar sands to provide feedstocks for hot water process
US4864075A (en) Dithiocarbamates for treating hydrocarbon recovery operations and industrial waters
Poirrier et al. Adsorption and concentration of dissolved carbon-14 DDT by coloring colloids in surface waters
US4445908A (en) Extracting alcohols from aqueous solutions
US5441156A (en) Process and recovering minerals from non-sulfidic ores by flotation
US6375853B1 (en) Methods of using modified natural products as dewatering aids for fine particles
US4575418A (en) Coal cleaning and the removal of ash from coal
Andersson et al. Enrichment of trace elements from sewage sludge fertilizer in soils and plants
US3957674A (en) Magnesium hydroxide suspension
US4392941A (en) Recovery of bitumen from tar sands sludge using additional water
US5096461A (en) Separable coal-oil slurries having controlled sedimentation properties suitable for transport by pipeline

Legal Events

Date Code Title Description
AS Assignment

Owner name: HENKEL KOMMANDITGESELLSCHAFT AUF AKTIEN (HENKEL KG

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNORS:KOESTER, RITA;LIPHARD, MARIA;SCHENKER, GILBERT;REEL/FRAME:006028/0012

Effective date: 19911121

CC Certificate of correction
FPAY Fee payment

Year of fee payment: 4

FPAY Fee payment

Year of fee payment: 8

REMI Maintenance fee reminder mailed
LAPS Lapse for failure to pay maintenance fees
FP Expired due to failure to pay maintenance fee

Effective date: 20050601